Stress comes in different forms—pain, hunger, fear, psychological upset. When we’re under stress, it’s often assumed that we are on heightened alert. If something hurts us, we imagine that an internal security system clicks on, scanning for other signs of danger. But a new study led by New York University neuroscientists reveals that being under acute stress diminishes our ability to pay attention to changes around us that might be threatening, like a swerving car or an unexpected shift in a person’s behavior. That delay in recognition may put us at risk of not responding appropriately to new dangers.
To understand the new study, it helps to understand stress. The body’s resting state is known as homeostasis. In that condition, heart rate, breathing, and all other systems tick along normally and relatively peacefully. Stress represents a physiological change that knocks you out of homeostasis. A part of the nervous system known as the HPA axis (a chain reaction involving the hypothalamus, pituitary and adrenal glands) kicks into action, releasing cortisol and other hormones to try to calm the body back down and return it to homeostasis. This means that when your body is under stress, it is aroused.
That is not always a bad thing. Think of your stress response as an upside-down U-shaped curve. Too little stress and you are under-aroused, too much and you are over-aroused. But there’s a point at the curve of the U where just the right amount of arousal can enhance performance. That fact contributes to the general sense that stress makes us more alert and responsive, and it explains why some people think they do best under pressure.